Process and apparatus for drawing polyester filaments



Nov. 10, 1970 A TAKAAKI FUKUSHIMA ETAL 3,539,680

PROCESS AND APPARATUS FOR DRAWING POLYESTER FILAMENTS Filed Aug. 7,. 1967 2 Sheets-Sheet 1 H9. 2 F/g.

NOV. 10; 1970 TAKAAKl FUKUSHIMA ETAL 3,539,680

PROCESS AND APPARATUS FOR DRAWING POLYESTER FILAMENTS Filed Aug. 7, 1967 2 Sheets-Sheet 2 STRESS STRAIN United States Patent 3,539,680 PROCESS AND APPARATUS FOR DRAWING POLYESTER FILAMENTS Takaaki Fukushima, Mihara-shi, Haruki Takizawa, Kikuo Hori, and Yoshito Sato, Matsuyama-shi, and Haruhiko Mizumori, Amagasaki-shi, Japan, assignors to Teijin Limited, Osaka, Japan, a corporation of Japan Filed Aug. 7, 1967, Ser. No. 658,799 Int. Cl. B29c 17/02 U.S. Cl. 264-290 Claims ABSTRACT OF THE DISCLOSURE A drawing process wherein fixation of the necking point is made certain by drawing undrawn polyester filaments while pressing the same onto a feed roller by a pressure roller provided at the side in contact with the feed roller heated at a predetermined temperature and said process is of non-friction type and an apparatus therefor.

The present invention relates to improved process and apparatus for drawing polyester filaments. More particularly, the present invention relates to a drawing apparatus wherein a heated roller and a pressure roller are positioned in novel correlated positions with respect to the drawing direction of the filaments and a novel drawing process for preparing polyester filaments having few flufi's and uniform dyeability.

Heretofore, upon drawing polyester filaments a process for continuous drawing which comprises providing a hot pin fixed between two rollers having different peripheral speeds, wrapping undrawn filaments around said hot pin by a desired number of times to impart heat necessary for drawing, at the same time, to fix a necking point by frictional resistance by the passage of the undrawn filaments run on said hot pin has been employed.

However, such a prior drawing process suffers certain disadvantages. In particular when high drawing speeds are used and when the total denier of the undrawn filaments is large, a large number of wraps around the hot pin is required in order to impart sufficient heat to the filaments necessary for drawing. However, due to frictional resistance of the pin, there is a limit to the number of wraps that can be provided around the pin. Further, there has been the disadvantage that friction can cause undesirable properties in the filaments. In particular, the necking point tends not to be fixed, but fluctuates thus causing flulfs and unevenness in dyeing. Further, abrasion of the hot pin per se readily takes place with the result that the pin has to be renewed at intervals.

On the other hand, there has been a drawing process not using a hot pin, but using a heated roller. However, in this case also, it was not possible to prevent fluctuation of the necking point.

An object of the present invention is to provide novel drawing process and apparatus having improved the aforementioned various defects in prior arts.

Other objects of the present invention will become apparent from the following description.

It has been found that these objects of the present in vention can be achieved by a process for drawing a bundie of undrawn thermoplastic saturated linear polyester filament having a filament denier below 150 and conice taining at least mol percent of ethylene terephthalate units, which comprises passing said undrawn filaments in a plurality of wraps around a positively rotated heated feed roller which cooperates with a freely rotatable pressure roller and from the feed roller to a draw roller which is rotating at a peripheral speed which is higher than the peripheral speed of the feed roller to thereby draw the filaments to 2.06.0 times its original length, the pressure roller having an elastic outer surface and being arranged so that at least the last wrap of the filament around the feed roller is pressed into contact with the outer surface of the feed roller, the point of contact being such that an angle 0: formed by a radius connecting the point where the filaments would depart from the feed roller if the pressure roller were not used with the center of the feed roller and a radius connecting the said point of contact with the center of the feed roller does not exceed 20, the surface temperature (T C.) of the heated feed roller being within the range of the second order translation point of the undrawn filaments (T C.) to a temperature 55 C. higher than the said second order transition point with the contact time of the undrawn filaments with the heated feed roller (t sec.) satisfying the equation:

According to the present invention there is also provided an apparatus for drawing a bundle of undrawn thermoplastic saturated linear polyester filaments having a filament denier below and containing at least 80 mol percent of ethylene terephthalate units, which comprises a positively rotatable feed roller which is adapted to heat undrawn filaments wound around the outer surface thereof and advance the heated fibers at a predetermined speed, means for imparting a pre-tension to the undrawn filaments before they are wound around the feed roller, a positively rotatable draw roller adapted to rotate at a peripheral speed which is higher than the peripheral speed of the feed roller for withdrawing the heated filaments from the feed roller and a freely rotatable pressure roller having an elastic outer surface and contacting the outer surface of the feed roller so that at least the last wrap of undrawn filaments is pressed into contact with the outer surface of the feed roller, the point of contact being such that an angle a formed by a radius connecting the center of the feed roller and the said point of contact and a radius connecting the center of the roller with the point where filaments would depart from the feed roller if the pressure roller were not used does not exceed 20.

Novel features of the present invention will be easily understood from consideration of the following description together with the accompanying drawings showing one embodiment of the apparatus used for the present invention.

FIG. 1 is a front elevation of the apparatus. FIG. 2 is a side elevation of the apparatus. FIG. 3 is an enlarged view for showing more clearly relative positions of the heated feed roller and the pressure roller shown in FIG. 2. FIG. 4 is a stress-strain curve of undrawn filaments measured by an Instron tensile tester.

In FIG. 1, undrawn filaments 2 are wound about a bobbin 1, 3 is a delivery roller rotating at a predetermined speed, rotating integrally with a nip roller 4 located thereabove, withdrawing the undrawn filaments 2 via a guide 5, 6 is a cylindrical heated feed roller mounted on a rotary shaft (not shown), accommodating inside the roller a heating member (not shown) to maintain a predetermined temperature. The heated feed roller 6 rotates at a surface speed slightly faster than that of the delivery roller 3, thereby imparting necessary pre-tension to the filaments. In the vicinity of the heated feed roller 6, a separator roller 8 is mounted and the filaments are wrapped around the heated feed roller 6 and separator roller 8 by a necessary number of times for heating the filaments and preventing them from slipping; 7 is a pressure roller rotating while being pressed onto the surface of the heated feed roller 6, pressing either several wraps of filaments containing at least the last wrap of filaments about to depart from the heated feed roller or only the last wrap onto the heated feed roller thereby the necking point is definitely fixed to the contact point of the two rollers without fluctuation. Under the heated feed roller 6, a slit heater 9 is provided, and further thereunder a drawing roller 10 and a separator roller 11 for the drawing roller are provided. The filaments are pulled by the drawing roller 10 and drawn. The drawn filaments are heat-treated by the slit heater 9 if necessary.

In practicing the process of the present invention, it is necessary that surface temperature (T C.) of the heated feed roller should be within the range of T C. to (T +55) C. where T C. is second order transition point of the undrawn filaments. When T C. becomes lower than T C., heat necessary for drawing is not imparted to the undrawn filaments, and as a result, dyeing unevenness is brought about in the drawn filaments. When T becomes higher than (T +55) C., the undrawn filaments stick to one another by fusing and crystallize partially, then drawing all the filaments without any breaking becomes diflicult. A preferable range of T is from (T +5) C. to (T C.

The time (2, second) that the filaments must contact with the heated feed roller in order that they receive satisfactory heating difiers naturally depending upon the surface temperature (T C.) of the heated feed roller; how ever 2 should satisfy the following equation:

and the filaments must be wrapped around the heated feed roller 6 for a time satisfying said formula. A preferable range of t is The most novel and important feature in the process of the present invention is the position of contact point where the pressure roller contacts with the surface of the heated feed roller shown in FIG. 2. Referring now to FIG. 3 which is an enlarged view of this portion, the position of the contact point is such that an angle oz formed by a radius connecting a point B where the filaments would depart from the heated feed roller if the pressure roller were absent or in an inoperative position, with the center A of the heated feed roller and a radius connecting the contact point D with center A does not exceed 20 C.

When said angle a measured in the opposite direction of proceeding of the filaments exceeds 20, because an inclination that the necking point fluctuates on the surface of arc BD of the heated feed roller increases, drawing is apt to become non-uniform and because the distance the drawn filaments contact the heated feed roller increases, due to the difference of the peripheral speed of the heated feed roller from the speed of the drawn filaments running on said roller, occurrence of flulfs is caused.

On the other hand, when said angle a measured in the direction of proceeding of the filaments exceeds 20, the drawn filaments get in contact with the pressure roller, not with the feed roller. Since the elastic material covering the surface of the pressure roller has a relatively low hardness, the contact results in damage to the surface of the pressure roller which in turn causes fluifs to occur and further increases the chances of filament breakage. At the same time, it becomes necessary to frequently replace the pressure roller. Further, the necking point will again fluctuate with the result that drawing becomes nonuniform, causing dyeing unevenness and the formation of fiutfs.

A preferable range of angle a is 0 to 3. By so doing, friction harmful to the filaments is minimized while maintaining sufficient heating and certain fixation of the necking point, as a result an excellent functional effect that makes it possible to carry out drawing at a high speed can be obtained.

A draw ratio which can be adopted in the process of the present invention is 2.0-6.0 and a drawing speed adoptable in the present invention is 50 m./min.-4500 1n./min., namely, an operation at a draw ratio and a drawing speed higher than those normally adopted is possible in the present invention.

Further, as one embodiment for preferably practising the process of the present invention, by a process wherein before the undrawn filaments pass around the heated feed roller, by imparting a pre-determined pre-tension within the range of 10-90% of the tension at which the neck occurs (Y) shown in a stress-strain curve of said undrawn filaments measured by an Instron tensile tester under conditions of at 20 C. temperature and 65% relative humidity shown in FIG. 4, said filaments without substantial drawing are fed to the heated feed roller.

According to experimental results, when this pre-tension is less than 10% of the tension at which the neck occurs it becomes diflicult to maintain the tension in the undrawn filaments at a predetermined value. On the other hand, when it becomes more than of said tension, local drawing is carried out to bring about dyeing unevenness and occurrence of fiuifs. Therefore, it is preferable that this pre-tension is within the range of 10-90% of the tension at which the neck occurs.

Heretofore as an apparatus to impart these pre-tensions, there have been a thread brake and a guide. However, it is diflicult for them to impart uniform and predetermined tension to filaments.

In the present invention, in which the undrawn filaments are wrapped around the heated feed roller, in order to minimize occurrence of fiulfs and dyeing unevenness, it is especially required to feed said filaments under a predetermined tension. Therefore, it is essentially preferable to securely hold and withdraw the filaments by using combination a of a nip roller and a delivery roller as shown in FIG. 1. In order to impart a preferable pretension as mentioned above, ratio of peripheral speeds of the delivery roller to the heated feed roller is generally within the range of 1:1.0011:1.030. However, a thread brake or a guide may be used, if it can impart uniform and predetermined tension.

In the apparatus used in the present invention, as a method of the urging of pressure roller into contact with the heated feed roller, a normal method using a spring, compressed air and oil pressure may be adopted.

By these means, the pressure roller is pressed onto the heated feed roller in such manner as the necking point of th undrawn filaments may be fixed.

The peripheral surface of the pressure roller is made of an elastic material such as rubber, and the surface hardness of said elastic material, as measured by JIS (Japanese Industrial Standard) K-630l, is preferably 30-95.

The surface of the heated feed roller may be a flat face, however, it may be a mat face.

As means for heating the heated feed roller, a normal heating means by electricity, steam, hot air, heated medium and infrared radiation may be adopted. Further, the heating may be effected from inside the roller, and the scaled surrounding space of the roller may be heated.

As means for heat treating the drawn filaments optionally provided between the heated feed roller and the drawing roller an apparatus normally used for heat setting a fiber such as heat plate and slit heater may be adopted. However, in view of the object of the present invention of trying to impart to the filaments as little friction as possible throughout the drawing step, use of a slit heater is most preferable.

As conditions for heat setting, a temperature of 120- 300 C. and a time of 001-2 seconds may be adopted.

Polyester filaments used in the present invention contain not less than 80 mol percent of ethylene terephthalate unit, and as other acid component, a dibasic acid such as phthalic acid, isophthalic acid, adipic acid, oxalic acid, sebacic acid, suberic acid, glutaric acid, pimelic acid, fumaric acid and succinic acid may be used. A polymerization degree modifier like propionic acid may be contained. As alcohol component, a divalent alcohol such as polymethylene glycol having 2-l0 carbon atoms (trimethylene glycol and butylene glycol) and cyclohexane dimethanol may be cited. And they may contain a small amount of the following compound as a modifier, 5-oXydimethyl isophthalate, 5-oxydirnethyl hexahydroisophthalate, benzene-1,3,5-tricarboxylic acid, para-carbomethoxy phenyl diethyl'phosphonate, 3,5-dicarboxy phenyl diethyl phosphonate, pentaerythritol, glycerol, glucose, phosphoric acid, triphenyl phosphate, tri-p-carbomethoxy phenyl phosphate, triphenyl phosphinate, triphenyl arsenite, tricapryl borate, sorbitan, trimesic acid and diethylene glycol.

Also, a small amount of another polymer such as polycarbonate, polyamide (such as nylon 6 or nylon 66), polyurethane and polyolefin, may be contained.

Although this invention may be applied to various polyesters described above, it is especially suitable for the drawing of filaments composed of polyethylene terephthalate alone.

The polyester filaments used in the present invention are filaments whose denier per monofilament is below 150 and a birefringence of undrawn filaments is within the range of 0.0005 to 0.0150. Undrawn filaments whose intrinsic viscosity is 0.3-1.2 may be used.

In the conventional drawing process, when undrawn filaments whose [1;] is below 0.5 are drawn, fluffs are brought about and satisfactory drawing could not be carried out. However, by the process of the present invention, it becomes possible to carry out satisfactory drawing of undrawn filaments whose [11] is below 0.5. Polyester fiber having such a low 1] value is valuable as a fiber improved in occurrence of pilling a common defect of a normal polyester fiber.

The cross sectional configuration of polyester filaments usable in the present invention may be normal circular, non-circular (triangular, pentagonal, flat, cross, etc.), hollow (doughnut, non-circular hollow). Especially when filaments having non-circular or non-circular hollow cross sectional configurations are drawn by the conventional drawing process, fiuffs and dyeing unevenness increase, however, according to the process of the present invention, it is possible to carry out drawing of such filaments without being accompanied by such shortcomings.

Explanations will be made hereinbelow about measuring methods described in the explanations of examples to be mentioned later.

(a) Measuring method of a second order transition point (T Tg is defined by A. Pace in US. Pat. specification No. 2,556,295 and measuring was carried out by a Volume Dilatometry method reported by Bekkedahl (I. Research N.B.S., 42, 145 (1949)). In the case of noncrystalline undrawn polyethylene terephthalate filaments, T is 69 C.

(b) Measuring method of an intrinsic viscosity [1 In o-chlorophenol 1.25% of the sample was dissolved at 100 C., specific viscosity [1 of the obtained solution was measured at 35 C. and [1 was sought from (c) Measuring method of a birefringence (An): It was measured by using a polarisation microscope having a crossed nickel prism reported by A.N.J. Hein in Text. Research 1., 22, 513 (1952).

(d) Measuring method of dyeing unevenness: A sample was knitted, and a knitted test piece was dyed in a solution containing 3% of a dyestufi? (Dispersed Scarlet B) based on said test piece by boiling at 100 C. for minutes. Dyeing unevenness of the dyed knitted test piece was adjudicated by naked eyes and the result Was converted to N.B.S. unit. Relationship of N.B.S. unit with adjudication by naked eyes is as follows.

N.B.S. Adjudication by naked eyes 0.0-0.5 Trace. 0.11.5 Slight. 1.5-3.0 Noticeable. 3.0-6.0 Appreciable. 6.0-12.0 Much. Above 12.0 Very much.

(e) Measuring method of stress unevenness of drawn filaments: It was measured by an Elasticity Meter Dynagraph II manufactured by Herbert Stein Co. A sample was caused to run at a measured speed of 24 m./min. and a draw ratio of 10% and variation of stress at that time was measured continuously. Difference of maximum stress from minimum stress at a sample filaent length of 8 m. was R, which was continuously measured for 10 times (measured for 3 m. 10:80 In. continuously).

Stress unevenness means an average value (H) of the so obtained Rs 10 (R Iii/10 The number of wraps of the filaments about the heated feed roller-7 Contact time of the filament with the heated feed roller- 0.775 second Temperature of the portion of the slit heater were filaments pass-240 C.

Properties of the obtained drawn heat-set filaments were as shown in the following Table l.

(f) Measuring method of fluifs of drawn filaments: Number of fluffs per 1,000,000 In. of drawn filaments was measured.

Now, the present invention will be explained with reference to the following examples, however, the present invention will not be limited thereby.

EXAMPLES 1-4 Controls 1-2 Polyethylene terephthalate chips having an intrinsic viscosity (1;) of 0.65 were melted at 288 C., extruded through a spinneret having orifices of diameters of 0.25 mm., wound at a speed of 930 m./inm. to become undrawn filaments whose total denier was 261.

This undrawn filaments had an intrinsic viscosity (7;) of 0.63, a second order transition point (T of 69 C., a birefringence (An) of 549 10' and tension at which the neck occurs of 0.36 g./d.

This undrawn filaments were drawn and heat-set by using the drawing apparatus shown in FIGS. 1 and 2 while varying the surface temperature of the heated feed roller under the following conditions.

Pre-tension0.10 g./d.

Draw ratio-3.67

Drawing speed-500 m./min.

Diameter of the heated feed roller--l00 mm.

TABLE 1 Surface temp of the heated Dyeing Stress roller Tenacity, Elongation, unevenuneven- Fluffs per 0.) g./d. percent ness ness 1,000,000 n1.

Control 1 65 4. 78 26. 4 10.0 36. 2 1. 2 Example 1. 70 4. 93 27. 3 1. 5 9. 0. 4 Example 2. 80 5.03 27. 5 0. 0 8. 3 0.2 Example 3 100 5.01 27.2 1.0 9.2 0.7 Example 4 120 4. 98 27. 9 2. 0 13. 4 1. 0 Control 2 125 4. 92 28. 0 2. 0 14. 0 4. 2

In Control 1 wherein the surface temperature of the heated feed roller was too low, values of dyeing unevenness and stress unevenness became very large, which showed uniform drawing was not carried out. In Control 2 wherein said surface temperature was too high, occurrence of flufis was high.

EXAMPLES 5-10 Controls 3-5 The undrawn filaments same as in Examples 1-4 were drawn and heat set by using the apparatus shown in FIGS. 1 and 2 while varying drawing speed and the number of times were outside this range, then dyeing uneveness and fiuffs were much.

EXAMPLES 1115 Controls 6-8 TABLE 3 Dyeing Stress Tenacity, Elongation, unevenuneven- Flufis pr.

Angle a percent ness ness 1,000,000 me Control 6 Upstream 6.08 28.0 0. 5 9. 2 4. 8 Example 11. Upstream 20. 5.01 27. 5 0. 5 8. 5 1. 2 Example 12. Upstream 10. 5. 09 27. 1 0.0 8. 7 0.8 Example 13. 0 5.12 28. 3 0.0 8. 4 0.2 Example 14 Downstream 10. 5.02 27.8 0. 5 8. 2 0.4 Example 15. Downstream 20- 5. 10 26. 9 0. 5 9. 6 0. 6 Control 7. Downstream 30 5. 04 27. 5 0. 5 8.9 1. 8 Control 8 Without a pressure roller- 5. 08 27. 0 0. 5 16. 7 1. 2

wraps of filaments around the heated feed roller under the following conditions.

Pre-tension0.10 g./d.

Draw ratio3.67

Diameter of the heated feed r0llerl00 mm.

Surface temperature of the heated feed roller-85 C. Temperature of the portion in the slit heater-240 C.

Properties of the obtained drawn heat-set filaments were as shown in Table 2.

Controls 9-26 The undrawn filaments same as those of Examples 1-4 were drawn and heat-set in accordance with the conventional drawing process using a hot pin under the following conditions.

TABLE 2 Contact time with Drawing the heated Dyeing Stress Number speed, feed roller, Tenacity, Elongation, unevenuneven- Flufis per of wraps m./min. sec. gJd. percent ness ness 1,000,000 In.

Control 3 7 12 32. 2 4. 98 27. 8 1. 5 8. 1 5. 9 7 64 6. 1 5. 10 26. 4 1.0 7. 7 2. 3 7 80 4. 8 5.03 27. 1 0. 5 8.0 0.6 7 640 0.45 5. 09 27.0 0. 0 8. 4 0.3 7 2560 0. 15 5. 08 27.3 0. 5 8.8 0. 7 7 2880 0. 13 5. 14 2G. 9 5. o 24. 6 2. 8 1 500 0. ll 4. 83 26. 8 5. 0 23. 5 3. 2 2 500 0.22 5. 03 27.3 0. 5 9. 3 1. 1 Example 10 8 500 0.88 5. 05 27. 5 0.0 8.0 0.2

The control time of undrawn filaments with the heated feed roller necessary for practising the process of the present invention obtained by calculation based on experimental conditions is within the range of 26.50 to 0.14

Pre-tension0. 10 g./ d. Draw ratio3 .67 Drawing speed-500 111./l11lll.

seconds, and the Controls 3, 4 and 5 wherein said contact 75 Diameter of a (mat faced) drawing pinmm.

The number of wraps filament around the drawing pin 2 times I Temperature of the portion in the slit heater where filarnent pass-240 C. Properties of the obtained drawn, heat-set filaments were as shown in Table 4 below.

10 paratus shown in FIGS. 1 and 2, this undrawn filaments were drawn and heat-set under the following conditions.

Pre-tension0.08 g./d.

Draw ratio-3.50

The number of wraps around the heated feed roller-8 times Drawing were carried out under the same conditions as mentioned above, except making the pin temperature 85 C. and varying drawing speed. Properties of the obtained drawn, heat-set filaments were as shown in Table 5 below.

Contact time with the heated feed roller0.52 second Surface temperature of the heated feed roller-83 C.

Diameter of the heated feed roller--100 mm.

Temperature of the portion in the slit heater Where the filaments passed220 C.

TABLE 5 Drawing Contact Tenacity, Elongation, Dyeing Stress Flntfs per speed, time with g./ percent Lmevenuneven- 1,000,000 n1.- mJmin. the pin, ness ness sec.

Control 15 2. 6 32. 2 5. 06 29. 3 1. 5 9. 8 6. 3 Control 16 13. 8 6. l 5. 21 28. 2 2. 12. 1. 8 Control 17 17. 3 4. 8 5. 29. 5 2. 0 13. 8 0. 9 Control 18 185 0. 45 4. 97 27. 8 2. 0 18. 4 0. 4 Control 19 553 0. 5. O9 29. 1 10. 0 64. 6 1. 4 Control 20 620 0. 13 4. 85 29. 6 12. 0 88. 7 18. 1 Control 21 12 6. 02 5. 18 26. 5 3. 0 25. 3 0. 2 Control 2 64 1. 5. 09 26. 2 4. 0 32. 6 0. 9 Control 2 80 1. 04 5. 11 27. 4 4. 0 37. 4 O. 7 Control 2 640 0. 13 4. 96 26. 8 12 0 62. 8 16. 7 Control 2 2560 0.03 Control 26 2880 0.03

When the drawing speed exceeded 600 m./min. unevenness increased and number of fluff increased, when said Properties of the obtained drawn, heat-set filaments were as shown in Table 6 below.

TABLE 6 Tension at which Undrawn the neck Dyeing Stress Chip filament occurs, Tenacity, Elongation, unevenuneven- Flufis per 7] 1] 0-) An g./ g./d. percent ness ness 1,000,000 in.

0. 36 67 326 1O- 0. 37 3. 13 12. 3 0. 0 12. 0 0. 8 0. 63 69 572X10- 0. 42 5. 02 27. 8 O. 0 11. 6 0. 4 0. 78 69 668 10- 0.45 6. 86 25. 9 0. 5 14. 9 0. 6

speed exceeded 800 m./min. fluff and filaments breakage occurred often and satisfactory drawing cannot be carried out.

From results of Controls 9-26, it was understood that the drawing process using a hot pin was remarkably inferior to the process of the present invention in dyeing uneveness, stress uneveness and fluflf.

EXAMPLES 16-18 Polyethylene terephthalate chips having various intrinsic viscosities (1 were melted, extruded through a spinneret having 48 orifices, would at a speed of 970 m./min. to obtain undrawn filaments of 349 denier. Using the ap- Controls 27-29 The undrawn filaments same as those of Examples 16- 18 were drawn and heat-set by the conventional drawing process using a hot pin under the following conditions.

Pre-tension-0.08 g./ d.

Draw ratio3.50

Drawing speed--8OO m./min.

Temperature of the drawing pin83 C.

Diameter of the drawing pinmm.

The number of wraps around the drawing pin-2 times Heat-setting temperature (hot plate)- C.

Properties of the obtained drawn, heat-set filaments Were as shown in Table 7.

In a drawing process using a hot pin, when undrawn filaments having an (1;) of 0.04 were drawn, many flufis were brought about, filament breakage was often and satisfactory drawing could not be carried out. In accordance with the process of the present invention, sufiiciently satisfactory results were obtained.

EXAMPLES 19-24 The undrawn filaments same as those of Examples 1-4 were drawn and heat-set under conditions same as in Ex- 12 contact time of the filaments with the heated feed roller of 0.54 second.

The so obtained drawn filaments having triangular cross sectional configuration has a tenacity of 5.00 g./d., an elongation of 28.0%, dyeing uneveness of 0.5, stress unevenness of 6.5 g. and 0.8 fiufi per 1,000,000 In.

Whereas, in said drawing, when the number of turns was 2 times, the drawn filaments had deteriorated properties of a tenacity of 5.08 g./d., an elongation of 26.0%, dyeing unevenness of 3.0, stress unevenness of 13.3 g.

amples 14 except making the temperature of the heated 10 d 14 mfg 1,000 000 feed roller 85 C. and varying pre-tension by adjusting the speed of the delivery roller. EXAMPLE 27 Properties of the obtained drawn, heat-set filaments Undrawn filaments consisting predominantly of polywere as shown in Table 8 below. ethylene terephthalate containing 11.8 mol percent of di- TABLE 8 Ratio of Variation Dyeing Stress roller of tension, Tenacity, Elongation, unevenunevon Flul'fs per speed Pretnsi0n,g. g./d. g./d. percent ness ness 1,000,000 I11.

Ex 19 1. 0008 0.03 i0. 01 5.10 28.4 1.5 13.2 29.6 Ex 20, 1.003 0.05 i0. 01 4.90 27.3 0.5 0.0 1.2 Ex. 21 1. 00s 0. i0. 01 5. 0e 27. 9 0. 0 7. 5 0. 4 Ex. 22 1. 012 0. 13 i0. 01 5.01 28. 5 0. 5 s. 4 0. 0 Ex. 23 1. 035 0. 36 :|:0. 02 5. 0s 27. 6 2. 5 16. 3 4. 5 Ex. 24 t 0. 01 =|=0. 08 5. 04 28. 0 4. 0 28.7 2. 1

speed of the heated feed roller 1 Ratio of roller speed=- speed of the delivery roller 2 Pretension imparted by a thread brake (guide).

The preferable range of pre-tension of this drawn filaethylene glycol of 175 denier having an [1;] of 0.52, a ments was 0.04-0.33 (g./d.), and drawing under condi- 3 second order transition point of 54 C., the tension at tions outside this range resulted in increase of unevenness which neck occurs of 0.24 g./d. and a An of 448x l05 and fiuff. In the process wherein pre-tension was imparted was drawn by using the apparatus employed in Example 1 by a guide, unevenness was much and the process was not under conditions of a pro-tension of 0.07 g./d., a tempreferable. perature of the heated feed roller of 70 C., the number EXAMPLE 25 5 of wraps of the filaments around said roller of 6 times, a draw ratio of 4.20, a drawing speed of 600 m./min. and a ig 232 5 5 ?ggie gi g fggz iggigg g l g g contact time of the filaments with the heated feed roller having 250 orifices of diameters of 0.35 mm, wound at of Second Whlle pressmg the Polnt the a Speed of 500 [IL/min. to Obtain undrawn filaments of ments aparted from the roller by an elastic roller. The 6141 denien The undrawn filaments had an [n] of 019, 40 obtained drawn filaments had dyeing unevenness of 0.5, a Tg of .5 C., a An of 203X10 5 and the tension at tress unevenness of 7.2 g., 1.1 finds/1,000,000 m., a which the neck occurs of 0.40 g./d. This undrawn filatenaclty of and an elongatlfm of 301%; In ments were drawn by using the apparatus shown in FIGS case, the number of turns was made 1 tlme, the obtained 1 and 2 under the following conditions drawn filaments had dyeing unevenness of 4.0, stress unevenness of 15.6 g., 8.3 Hulk/1,000,000 In., a tenaclty of g p i g n 750 c 4.50 g./d. and an elongation of 28.5%.

em eratureo t e ea c ee ro er Nurri ber of turns around the heated feed roller6 times MP E 28 Contact time of the filaments with the heated feed roller U d fil t f 171 d i i ti f l 5.35 second ethylene terephthalate containing 0.2 mol percent of pen- Pre-tension0.12 g./d. taerythritol having an intrinsic viscosity [7]] of 0.63, a Draw ratio-5.97 second order transition point of 67 C., the tension at Temperature of the portion of the Slit heater Where the which the neck occurs of 0.40 g./d. and a An of 523 10 filaments passl95 C. were drawn by the apparatus employed in Example 1,

The obtained drawn filaments had a tenacity of 8-59 under conditions of a pre-tension of 0.09 g./d., a drawing g./d., an elongation of 11.2%, 2.5 fluffs per 1,000,000 Inspeed of 500 m./min., a draw ratio of 3.40, a temperad drawing Went without y trouble. W n ease ture of the heated feed r01lr of 85 c., the number of no pressure T011617 Was used, although there s 110 difief- Wraps of the filaments around the heated feed roller of 6 ence in tenacity had elongation, fluff increased times, a contact time of the filaments with the heated feed 5.6/ 1,000,000 In. roller of 0.42 second and the angle a and the contact pres- EXAMPLE 26 sure of an elastic roller same as those of Example 26.

Chi s of a 01 eth lene tere hthalate-isophthalate co- The obtamed firawn filaments h a tenaclty of polym r conta i niri g 4 .5 mol peiicent of isophthalic acid an elongatlon of 283% dyelng unevemless of ([flzo'64) were melted at 0 C extruded through a stress unevenness of 7.6 g. and 1.2 finds/1,000,000 H50 0 spinneret having 24 Y-shaped orifices of diameters of 5 whfireas m case the dlawmg Speed a made 0 0.25 mm, Wound at a Speed of 1000 nL/min to Obtain m./mm., a contact time of the filaments W1th the heated undrawn filaments of 172 denier whose cross sectional feed r0116 became Second and the Obtamed firawn configuration was triangular. This undrawn filaments had filaments a tenaclty of gJd't an elonganon an [n] of 062 a Tg of 680 0 had the tension at which 27.5%, dyelng uneer/mess o 5.0, stress unevenness o the neck Occurs of 0.38 g./d. and flu S IOOOOOO This undrawn filaments were drawn by using the ap- EXAMPLES 9 30 paratus employed in Example 1 under the conditions of a pretension of 0.09 g./d. a drawing speed of 800 m./min., Undrawn filaments were drawn under conditions same a draw ratio of 3.60, a temperature of the heated feed as in Examples 510 and when comparison was made in roller of 83 C., the number of turns of 8 times and a case a slit heater having effective length of 400 mm. for

13 heat-setting was used and in case a hot plate was used, the results as shown in Table 9 below were obtained. Temperature of the portion of the slit heater where the filaments passed was 240 C. and surface temperature of thermoplastic saturated linear polyester filaments having a filament denier below 150 and containing at least 80 mol percent of ethylene terephthalate units, which comprises a positively rotatable feed roller which is adapted the hot plate was 160 C. to heat undrawn filaments wound around the outer sur- TABLE 9 Heat- Dyeing Stress treating Tenacity, Elongation, unevenuncven- Flutfs per apparatus g./d. Percent ness ness 1,000,000 in.

Ex. slit heater 5.02 28.8 0.0 8.6 0.4 Ex. 30 Hotplate 5.00 28.2 05 12.4 1.8

What is claimed is: face thereof and advance the heated fibers at a predeter- 1. Aprocess for drawing a bundle of undrawn thermomined speed, means for imparting a pre-tension to the plastic saturated linear polyester filament having a fil-a- 5 undrawn filaments before they are wound around the ment denier below 150 and containing at least 80 mol feed roller, a' positively rotatable draw roller adapted to percent of ethylene terephthaltate units, which comprises rotate at a peripheral speed which is higher than the passing said undrawn filaments in a plurality of wraps peripheral speed of the feed roller for withdrawing the around a positively rotated heated feed roller which coheated filaments from the feed roller and a freely rotatoperates with a freely rotatable pressure roller and from 20 able pressure roller having an elastic outer surface and the feed roller to a a roller which is rotating at a contacting the outer surface of the feed roller so that at Peripheral Speed which is higher than the Peripheral Speed least the last wrap of undrawn filaments is pressed into 0f the feed roller to thereby draw the filaments t0 contact with the outer surface of the feed roller, the point times its original length, the pressure roller having an of Contact b i h th t an angle f d b elastic Outer Surface and being arranged so that at least radius connecting the center of the feed roller and the the last Wrap of the filament around the feed roller is said point of contact and a radius connecting the center Pressed into Contact with the Outer Shrfaee 0f the feed of the roller with the point where filaments would depart roller, the Point of Contact being Such that an angle from the feed roller if the pressure roller were not used formed by a radius conencting the point where the filadoes not exceed 20a ments would depart from the feed roller if the pressure 3 The apparatus of l i 7, further including e ns roller were not used with the center of the feed roller and f h treating h fil m t d i h i passage f m a radius connecting the said point of contact with the the f d u the draw h center of the feed roller does not exceed 20, the surface 9 The apparatus of claim 8 h i h means f temperature (T C.) of the heated feed roller being within heat treating the fila ent i a li h the range of the second order transition point of the un- The apparatus f l i 7, wherein the pretension drawn filamentS g to a temperature 55 higher means comprises a nip roller and a delivery roller which than the Said Second Order translation Point with the in use of the apparatus is adapted to rotate at a peripheral contact time of the undrawn filaments with the heated speed in the range of 1/1.0001 to 1/1030 of the peripheral feed roller (t sec.) satisfying the equation: Speed f the fe d h 0.120(TT )+28.420? t;0,003 (T-T +0.189 References Cited 2. The process of claim 1 wherein the contact time UNITED STATES PATENTS satisfies the equation: 3 092 891 6/ 1963 Baratti 264-290 g)+ g+ 3:256:134 6/1965 Rice 151 ...172 3. A process described in claim 1, wherein a pre-tension 3,302,385 2/ 1967 Ruddell et a1. is imparted to the undrawn filaments before they are 3,358,344 12/1967 Daniel 264-168 X passed around the feed roller, such a pretension being 3,374,302 3/1968 Stanley 264-468 X within the range of 10 to 90% of the tension at which a 3,376,622 4/1968 Stanley 264-168 neck occurs as shown in a stress-strain curve of the un- 3,379,809 4&1968 Woods 264168 drawn filaments measured at a temperature of 20 C. and 3,381,461 5/1968 Chubb 264-168 X a relative humidity of 3,404,525 10/ 1968 Tompkins 57140 4. A process described in claim 1, wherein said polyester filaments consist of polyethylene terephthalate. 65 JULIUS FROME, Primary Examiner 5. A process described in claim 1 wherein said surface temperature of said heated feed roller is within the range of (T +5) C. (T +25) C.

6. A process described in claim 1 wherein said angle (a) is within the range of 0 to 3.

7. An apparatus for drawing a bundle of undrawn J. H. WOO, Assistant Examiner U.S. Cl. X.R. 

